1. Technical Field
The present invention relates to a bottle-shaped synthetic resin container having a circumferential groove extending along the surface of the container body portion.
2. Prior Art
Generally, bottle-shaped container comprised of a synthetic resin such as polyethyleneterephthalate (“PET”) has a reduced thickness of the body portion. As such, the appearance tends to deteriorate due to the deformation of the body portion into elliptical shape upon internal pressure reduction of the container, besides that the self-standing stability of the container tends to be lowered as a result of deformation of the container. In these respects, as compared to bottle-shaped containers made of glass, aluminum or the like, bottle-shaped synthetic resin container still has a room for further improvement in terms of its applicability to a filling line wherein the containers are transferred by gliding them along the bottom surface, or to an automatic vending machine capable of storing and dispensing a number of bottles.
In order to eliminate these problems, there is known a technology wherein the body portion of the bottle-shaped synthetic resin container has an outer surface formed with one or more circumferential grooves, which are utilized for allowing a contractive deformation of the bottle in the longitudinal direction of the bottle, so as to enhance the pressure reduction absorption property against the internal pressure reduction of the container, and thereby compensate for the pressure reduction resistance and the buckling strength. For example, Japanese Unexamined Patent Publication JP-09-272523 A1 discloses a bottle-shaped synthetic resin container wherein the groove bottom portions of the circumferential groove are arranged into a polygonal shape as seen in a plane perpendicular to the center axis of the container. However, in this instance, the corners of the polygon formed by relatively narrow groove bottom portions function as beams, which not only impede the contractive deformation of the container in the longitudinal direction of the bottle by utilizing the groove portions, but also require a relatively strict manufacturing control upon blow molding or the like.
Accordingly, there is a need for an improved synthetic resin bottle, which does not require a strict manufacturing control, which is formed in the outer surface of the body portion with a circumferential groove of more simplified shape, and which yet effectively suppresses elliptical deformation of the bottle body portion due to the internal pressure reduction of the container, thereby sufficiently exhibiting the required pressure reduction resistance or buckling strength.